Explosively operated deep water tool

ABSTRACT

A piston is slidably mounted in the opposite end portions of a barrel, the central portion of which is spaced from the piston. Mounted on the front end of the piston is an operating member, such as a cable cutter. The rear end of the barrel is provided with means for firing an explosive charge to drive the piston forward. A collar is joined to the piston and slidably engages the wall of the central portion of the barrel. This wall has openings through it behind the collar so that water pressure against the front end of the piston will be at least partly counterbalanced by water pressure against the rear face of the collar.

United States Patent 1 1 3,763,738 Temple Oct. 9, 1973 [S4] EXPLOSIVELY OPERATED DEEP WATER 3,662,634 5/1972 Burke 114/221 A TOOL Inventor: Ernest Temple, Murrysv ille, Pa,

Assignee: Mine Safety Appliances Company.

Pittsburgh, Pa.

Filed: July 3, 1972 Appl. No.: 268,569

References Cited UNITED STATES PATENTS 4/1966 Temple et a1. 30/277 R 12/1969 9/1971 Brizzolara 812 Riordan 114/221 A Primary ExaminerSamuel W. Engle Attorney--Brown, Murray, Flick and Peckham [5 7] ABSTRACT A piston is slidably mounted in the opposite end portions of a barrel, the central portion of which is spaced from the piston. Mounted on the front end of the piston is an operating member, such as a cable cutter. The rear end of the barrel is provided with means for firing an explosive charge to drive the piston forward. A collar is joined to the piston and slidably engages the wall of the central portion of the barrel. This wall has openings through it behind the collar so that water pressure against the front end of the piston will be at least partly counterbalanced by water pressure against the rear face of the collar.

6 Claims, 3 Drawing Figures EXPLOSIVELY OPERATED DEEP WATER TOOL Explosively actuated tools are used underwater for a number of different purposes, such as for cutting chains or cables or driving pointed studs into metal plates. In such tools the explosion ofa charge drives a piston forward in a barrel and the piston drives a suitable operating member, such as a cutter or stud-driving element. These tools operate successfully underwater as long as they are not used at too great a depth, but at great depths, such as 20,000 feet or more, they become practically inoperative because the pistons cannot be driven forward against the resistance of the extremely great water pressure at those depths.

It is among the objects of this invention to provide an explosively actuated tool that can be used satisfactorily at great depths in the ocean as at sea level, and that is very simple in construction.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which FIG. 1 is a fragmentary side view, partly in section;

FIG. 2 is a horizontal section partly in elevation; and

FIG. 3. is an enlarged cross section taken on the line IIlIll of FIG. 2.

Referring to the drawings, a forked member 1 has a cross bar 2 extending across its open front end, in which the bar is held by screws 3. The opposite end of the fork is provided with a rearwardly extending tubular projection 4. Screwed onto this projection is the front end of a sleeve 5, on the rear end of which a cap 6 is screwed. The rear end portion of the sleeve preferably has the same internal diameter as the tubular projection of the fork, but the front portion of the sleeve has a larger internal diameter. The sleeve and the tubular part of the fork together form a barrel in which a rod like piston 7 is disposed. As shown in FIG. 2, this piston is slidably mounted in the front and rear end portions of the barrel but is spaced from the wall or inner surface of the central portion.

The front end of the piston projects a short distance from the barrel and carries an operating member, which may be a cutter 9 or chisel. This cutter is rigidly mounted in a slot in the front end portion of the piston, with the opposite ends of the chisel extending into parallel guide slots 10 in the opposite sides of the fork, wich forms a housing for the cutter. To drive the chisel forward, an explosive charge is located at the rear end of the barrel. One way of doing this is to provide the rear end of the piston with an axial bore 11, in which a cartridge 12 is placed. The rear end of the cartridge engages a washer 13 that serves as a breech block and that is held against the cartridge by cap 6. A short distance in front of the washer the cartridge is provided with a peripheral groove containing a sealing washer 14. The cartridge can be fired electrically by current supplied to it through wires 15 extending through washer l3 and a tube 16 in which the wires are sealed. The inner end of this tube is sealed in a central opening in cap 6.

When the cartridge is fired, the force of the explosion drives the piston forward in the barrel and thereby pushes or drives the cutter forward in its housing. The cutter is designed to cut through cables 17 extending through the housing in front of the cutter. The cables can be inserted in the fork by first removing cross bar 2 to admit them, and then replacing the bar. The face of the bar that faces the cutter is provided with a longitudinal groove in which there is a rod 18 of soft metal that serves as a shock absorber to receive and stop the cutter after it passes through the cables.

When such a tool is used in water at great depths the front end of the piston is exposed to extremely high water pressure pressing rearwardly against it. It will be seen that the greater the depth at which the tool is used the more difficult it would be for the explosive charge to overcome the resistance of this pressure. It is a feature of this invention, therefore, that the tool is so constructed that the pressure of the water tendency to hold the piston in the barrel can be counteracted to any desired extent, even to the point where it is completely overcome so that there will be no more difficulty in firing the tool at a great depth than firing it in air.

Accordingly, the piston is encircled by a collar 20 in the annular space inside the enlarged central portion of the barrel. The collar is rigidly joined to the piston, such as by being welded to it or being integral with it. With the piston retracted as shown in FIG. 2, the collar is near to, but spaced from, the rear end of the annular space just mentioned. The piston slidably engages the encircling wall of the barrel. Behind the collar this space is connected with the outside of the tool by means of radial openings 21 in the barrel, so that the space directly behind the collar is exposed to the surrounding water. On the other hand, water is kept out of the space in front of the collar by providing the collar with a circumferential groove in which a sealing ring 22 in mounted that tightly engages the encircling wall of the barrel, and by also providing the piston with such a groove and sealing ring 23 inside the front end portion of the barrel. To keep water behind the collar from seeping back between the barrel and the piston and into recess 14 behind the piston, the rear end of the piston likewise is provided with a circumferential groove containing a sealing ring 24.

It will be seen that the water pressure against the front end of the piston is counteracted more or less by the water pressure against the rear face of collar 20, depending upon the area of that face. If its area is less than the cross sectional area of the front end of the piston in the front end of the barrel, the pressure of water rearwardly against the piston will be only partly counterbalanced by the forward pressure against the collar. Nevertheless, this will allow the tool to be used at a greater depth than otherwise would be the case. However, in order not to put any limitation on the depth at which the tool can be used, it is preferred that the two pressures be substantially balanced. This can be done by making the area of the rear face of the collar substantially equal to the cross sectional area of the front end of the piston, so that there is much water pressure tending to move the piston forward as there is to moving it backward. With such a relationship of the two areas, when the cartridges are tired the piston will offer no more resistance to forward movement in the barrel at any depth of water than it would in air. In other words, the explosive charge does not have to overcome any appreciable resistance of the piston to moving forward, so the full force of the explosion can be applied to the cutter.

Although the opposing pressures just referred to may be balanced before the tool is fired, some resistance may be met if the openings 21 in the barrel are not large enough to allow water to rush in behind the collar fast enough to keep the space behind it filled as it moves forward. Therefore, for best results, the total cross sectional area of these openings should be at least as great as the area of the rear face of the collar.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A deep water explosively actuated tool comprising a barrel having an open front and a rear end, the central portion of the barrel having a larger internal diameter than the end portions thereof, a piston slidably mounted in said end portions of the barrel but spaced from the inner surface of said central portion, an operating member mounted on the front end of the piston, means at the rear end of the barrel for detonating an explosive charge for driving the piston forward in the barrel, and a collar joined to the piston and slidably engaging the inner surface of said central portion of the barrel, the wall of said central portion being provided with openings behind the collar connecting the inside of the barrel with the outside, whereby water pressure against the front end of the piston will be at least partly counterbalanced by water pressure against the rear face of the collar.

2. A tool according to claim 1, in which said piston is provided inside said end portions of the barrel with circumferential grooves, and sealing rings in said grooves tightly engaging said end portions.

3. A tool according to claim 1, in which the total cross sectional area of said openings is at least as great as the area of the rear face of said collar.

4. A tool according to claim 1, in which the area of the rear face of said collar is substantially equal to the cross sectional area of the piston in the front end of the barrel.

5. A tool according to claim 1, in which said piston is provided inside said end portions of the barrel with circumferential grooves, sealing rings in said grooves tightly engaging said end portions, the periphery of said collar being provided with a circumferential groove, and the collar including a sealing ring in its groove tightly engaging said wall of the central portion of the barrel.

6. A tool according to claim 5, in which the area of the rear face of said collar is substantially equal to the cross sectional area of the piston in the front end of the barrel, and the total cross sectional area of said openings is at least as great as the area of the rear face of the collar. 

1. A deep water explosively actuated tool comprising a barrel having an open front and a rear end, the central portion of the barrel having a larger internal diameter than the end portions thereof, a piston slidably mounted in said end portions of the barrel but spaced from the inner surface of said central portion, an operating member mounted on the front end of the piston, means at the rear end of the barrel for detonating an explosive charge for driving the piston forward in the barrel, and a collar joined to the piston and slidably engaging the inner surface of said central portion of the barrel, the wall of said central portion being provided with openings behind the collar connecting the inside of the barrel with the outside, whereby water pressure against the front end of the piston will be at least partly counterbalanced by water pressure against the rear face of the collar.
 2. A tool according to claim 1, in which said piston is provided inside said end portions of the barrel with circumferential grooves, and sealing rings in said grooves tightly engaging said end portions.
 3. A tool according to claim 1, in which the total cross sectional area of said openings is at least as great as the area of the rear face of said collar.
 4. A tool according to claim 1, in which the area of the rear face of said collar is substantially equal to the cross sectional area of the piston in the front end of the barrel.
 5. A tool according to claim 1, in which said piston is provided inside said end portions of the barrel with circumferential grooves, sealing rings in said grooves tightly engaging said end portions, the periphery of said collar being provided with a circumferential groove, and the collar including a sealing ring in its groove tightly engaging said wall of the central portion of the barrel.
 6. A tool according to claim 5, in which the area of the rear face of said collar is substantially equal to the cross sectional area of the piston in the front end of the barrel, and the total cross sectional area of said openings is at least as great as the area of the rear face of the collar. 